Electrical balanced duplexer-based duplexer

ABSTRACT

An electrical balance duplexer (EBD) may be used to isolate a transmitter and receiver that share a common antenna. By using impedance gradients to provide impedances that cause balance-unbalance transformers (balun) of the EBD to cut-off access to the common antenna rather than duplicate the antenna impedance, the EBD is balanced. Such cut-offs may have a lower insertion loss than an EBD that merely duplicates the antenna impedance to separate the differential signals of the receiver/transmitter from the common mode signal.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/582,769, now patented as U.S. Pat. No. 10,938,542, entitled“ELECTRICAL BALANCED DUPLEXER-BASED DUPLEXER”, filed on Sep. 25, 2019,which is incorporated by reference herein in its entirety for allpurposes.

BACKGROUND

The present disclosure relates generally to wireless communicationsystems and, more specifically, to systems and methods for electricalbalanced duplexer (EBD)-based power amplifier duplexers (PADs).

This section is intended to introduce the reader to various aspects ofart that may be related to various aspects of the present disclosure,which are described and/or claimed below. This discussion is believed tobe helpful in providing the reader with background information tofacilitate a better understanding of the various aspects of the presentdisclosure. Accordingly, it should be understood that these statementsare to be read in this light, and not as admissions of prior art.

Transmitters and receivers may be coupled to an antenna to enable anantenna to both receive and transmit from an electronic device. Certainof these electronic devices may use PADs to isolate the transmitter andreceiver ports from each other and control connection of thetransmitters/receivers to the antenna. The PADs may include multipleduplexers and switches to provide isolation between the transmitter andreceiver ports. Since the applications for the antenna, thetransmitters, and the receivers may be diverse, the PADs may includenumerous band pass filters that are frequency-dependent. In other words,to increase flexibility additional band pass filters may be added to thePAD. However, additional band pass filters consume additional space andadd costs to manufacture of the electrical device.

SUMMARY

A summary of certain embodiments disclosed herein is set forth below. Itshould be understood that these aspects are presented merely to providethe reader with a brief summary of these certain embodiments and thatthese aspects are not intended to limit the scope of this disclosure.Indeed, this disclosure may encompass a variety of aspects that may notbe set forth below.

Certain wireless electronic devices use duplexers to enable transmittersand receivers to share an antenna. In some situations, the electronicdevice may be used across multiple different frequencies. An electricalbalance duplexer (EBD) may be used to accommodate dynamic frequencyusage compared to arrays of pass-band filters. The EBD may includebalance-unbalance transformer (balun) circuits that include respectivebaluns that are coupled to impedance gradients that provide a respectiveimpedance at a corresponding frequency to enable/block traversal of thebalun. For example, some embodiments, may include a transmitter balunthat is configured to receive a first impedance (e.g., a high impedance)at a first frequency from a transmitter impedance gradient to blocksignals from the antenna from crossing the transmitter balun to thetransmitter while enabling signals from the transmitter to traverse thetransmitter balun using a second impedance (e.g., a low impedance) at asecond frequency from the transmitter impedance gradient. This frequencydivision is applied by the EBD because the first and second frequenciesare different. For instance, the first and second frequency may fall indifferent (i.e., non-overlapping frequency bands).

A receiver balun may function similarly to the transmitter balun. Forexample, the receiver balun that is configured to receive a firstimpedance at a first frequency from a receiver impedance gradient toblock signals from the transmitter from crossing the receiver balun tothe receiver while enabling signals from the antenna to traverse thereceiver balun using a second impedance at a second frequency from thereceiver impedance gradient. This frequency division is applied by theEBD because the first and second frequencies are different. Forinstance, the first and second frequency may fall in different (i.e.,non-overlapping frequency bands).

In some embodiments, the impedance gradients may be assisted usingimpedance tuners that reduce demands on the impedance gradients. Forexample, the impedance tuners may provide a low impedance in a pass bandwhile matching an impedance of a corresponding impedance gradient in ablock band.

BRIEF DESCRIPTION OF THE DRAWINGS

Various aspects of this disclosure may be better understood upon readingthe following detailed description and upon reference to the drawings inwhich:

FIG. 1 is a block diagram of an electronic device that includes aduplexer, in accordance with an embodiments of the present disclosure;

FIG. 2 is a perspective view of a notebook computer representing anembodiment of the electronic device of FIG. 1;

FIG. 3 is a front view of a hand-held device representing anotherembodiment of the electronic device of FIG. 1;

FIG. 4 is a front view of another hand-held device representing anotherembodiment of the electronic device of FIG. 1;

FIG. 5 is a front view of a desktop computer representing anotherembodiment of the electronic device of FIG. 1;

FIG. 6 is a front view and side view of a wearable electronic devicerepresenting another embodiment of the electronic device of FIG. 1;

FIG. 7 is a schematic diagram of the duplexer of FIG. 1 having anelectrical balance duplexer (EBD), in accordance with embodiments of thepresent disclosure;

FIG. 8 is a schematic diagram for an alternative embodiment of the EBDof FIG. 7 having a transmitter impedance gradient and a receiverimpedance gradient, in accordance with embodiments of the presentdisclosure;

FIG. 9 is a schematic diagram of the EBD of FIG. 8 with the transmitterimpedance gradient causing a transmitter balun to enable transmission ofsignals to an antenna and the receiver impedance gradient causing areceiver balun to block transmission of the signals to the receiver, inaccordance with embodiments of the present disclosure;

FIG. 10 is a schematic diagram of the EBD of FIG. 8 with the transmitterimpedance gradient causing a transmitter balun to block transmission ofsignals having a transmission frequency from the transmitter to anantenna and the receiver impedance gradient causing a receiver balun toenable transmission of signals having a receive frequency to thereceiver, in accordance with embodiments of the present disclosure;

FIG. 11 is a schematic diagram of the EBD of FIG. 8 with impedancetuners for each impedance gradient, in accordance with embodiments ofthe present disclosure;

FIG. 12 is a schematic diagram of the EBD of FIG. 11 with differentialsignals to be transmitted from the transmitter and differential signalsto be received by the receiver, in accordance with embodiments of thepresent disclosure;

FIG. 13 is an alternative embodiment of the EBD of FIG. 8 with theimpedance gradients and impedance tuners on a same side of acorresponding balun with the transmitter/receiver, in accordance withembodiments of the present disclosure; and

FIG. 14 is a block diagram of process used by the EBD of FIGS. 8-13, inaccordance with embodiments of the present disclosure.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

One or more specific embodiments will be described below. In an effortto provide a concise description of these embodiments, not all featuresof an actual implementation are described in the specification. Itshould be appreciated that in the development of any such actualimplementation, as in any engineering or design project, numerousimplementation-specific decisions must be made to achieve thedevelopers' specific goals, such as compliance with system-related andbusiness-related constraints, which may vary from one implementation toanother. Moreover, it should be appreciated that such a developmenteffort might be complex and time consuming, but would nevertheless be aroutine undertaking of design, fabrication, and manufacture for those ofordinary skill having the benefit of this disclosure.

Electronic devices may utilize one or more duplexers. Duplexers aredevices that enable bidirectional communication over a single path whileseparating components that utilize the single path. For example,duplexers may separate a receiver for the electronic device from atransmitter for the electronic device that both share an antenna of theelectronic device. Conventional duplexers may include filters of anykind to achieve this separation. For example, duplexers may includesurface-acoustic wave (SAW) filters and/or bulk-acoustic waves (BAW)filters based on microacoustic principles or may include aninductor-capacitor-resistor (LCR) filter based on resonating circuits ofinductors and capacitors to separate the transmitter and the receiver.

In addition to or alternative to SAW/BAW filters, a CMOS N-Path filter,a spatio-temporal circulator, or an electrical balanced duplexer (EBD)may be used in the duplexers. The EBD is a duplexer, which uses abalance-unbalance transformer (balun) in order to separate thedifferential signal from the common mode signal.

A substantial disadvantage of using the N-Path filter, spatio-temporalcirculator, or the EBD exists in that these technologies have a higherinsertion loss compared to using SAW/BAW filters. A further drawbackregarding the EBD is that the traditional EBD uses an active replica ofan antenna impedance in order to reach a highest isolation. Any antennaimpedance shift may disturb the duplex function and degrade theisolation between the transmit path and the receive path. As discussedbelow in more detail, the EBD discussed herein differs from traditionalEBDs in that a balun of the disclosed EBD in a balanced state is used tocut off the path to the antenna and not just to separate thedifferential signals of the receiver/transmitter from the common modesignal.

With the foregoing in mind, there are many suitable electronic devicesthat may benefit from the embodiments of duplexers described herein.Turning first to FIG. 1, an electronic device 10 according to anembodiment of the present disclosure may include, among other things,one or more processor(s) 12, memory 14, nonvolatile storage 16, adisplay 18, antenna(s) 20, input structures 22, an input/output (I/O)interface 24, a network interface 25, and a power source 29. The variousfunctional blocks shown in FIG. 1 may include hardware elements(including circuitry), software elements (including computer code storedon a computer-readable medium), or a combination of both hardware andsoftware elements. It should be noted that FIG. 1 is merely one exampleof a particular implementation and is intended to illustrate the typesof components that may be present in electronic device 10.

By way of example, the electronic device 10 may represent a blockdiagram of the notebook computer depicted in FIG. 2, the handheld devicedepicted in FIG. 3, the handheld device depicted in FIG. 4, the desktopcomputer depicted in FIG. 5, the wearable electronic device depicted inFIG. 6, or similar devices. It should be noted that the processor(s) 12and other related items in FIG. 1 may be generally referred to herein as“data processing circuitry.” Such data processing circuitry may beembodied wholly or in part as software, firmware, hardware, or anycombination thereof. Furthermore, the data processing circuitry may be asingle contained processing module or may be incorporated wholly orpartially within any of the other elements within the electronic device10.

In the electronic device 10 of FIG. 1, the processor(s) 12 may beoperably coupled with the memory 14 and the nonvolatile storage 16 toperform various algorithms. Such programs or instructions executed bythe processor(s) 12 may be stored in any suitable article of manufacturethat includes one or more tangible, computer-readable media at leastcollectively storing the instructions or routines, such as the memory 14and the nonvolatile storage 16. The memory 14 and the nonvolatilestorage 16 may include any suitable articles of manufacture for storingdata and executable instructions, such as random-access memory,read-only memory, rewritable flash memory, hard drives, and opticaldiscs. In addition, programs (e.g., an operating system) encoded on sucha computer program product may also include instructions that may beexecuted by the processor(s) 12 to enable the electronic device 10 toprovide various functionalities.

In certain embodiments, the display 18 may be a liquid crystal display(LCD), which may allow users to view images generated on the electronicdevice 10. In some embodiments, the display 18 may include a touchscreen, which may allow users to interact with a user interface of theelectronic device 10. Furthermore, it should be appreciated that, insome embodiments, the display 18 may include one or more organic lightemitting diode (OLED) displays, or some combination of LCD panels andOLED panels.

The input structures 22 of the electronic device 10 may enable a user tointeract with the electronic device 10 (e.g., pressing a button toincrease or decrease a volume level). The I/O interface 24 may enableelectronic device 10 to interface with various other electronic devices,as may the network interface 25. The network interface 25 may include,for example, one or more interfaces for a personal area network (PAN),such as a Bluetooth network, for a local area network (LAN) or wirelesslocal area network (WLAN), such as an 802.11x Wi-Fi network, and/or fora wide area network (WAN), such as a 3rd generation (3G) cellularnetwork, universal mobile telecommunication system (UMTS), 4thgeneration (4G) cellular network, long term evolution (LTE) cellularnetwork, or long term evolution license assisted access (LTE-LAA)cellular network, 5th generation (5G) cellular network, and/or 5G NewRadio (5G NR) cellular network. The network interface 25 may alsoinclude one or more interfaces for, for example, broadband fixedwireless access networks (WiMAX), mobile broadband Wireless networks(mobile WiMAX), asynchronous digital subscriber lines (e.g., ADSL,VDSL), digital video broadcasting-terrestrial (DVB-T) and its extensionDVB Handheld (DVB-H), ultra-Wideband (UWB), alternating current (AC)power lines, and so forth. For example, network interfaces 25 may becapable of joining multiple networks, and may employ one or moreantennas 20 to that end. Additionally or alternatively, the networkinterfaces 25 may include at least one duplexer 26 that enables multiplecomponents (e.g., the receiver 27 and the transmitter 28) with separatepaths (e.g., transmit path and receive path) to use one of the antennas20 while providing separation between the multiple components. Asfurther illustrated, the electronic device 10 may include a power source29. The power source 29 may include any suitable source of power, suchas a rechargeable lithium polymer (Li-poly) battery and/or analternating current (AC) power converter.

In certain embodiments, the electronic device 10 may take the form of acomputer, a portable electronic device, a wearable electronic device, orother type of electronic device. Such computers may include computersthat are generally portable (such as laptop, notebook, and tabletcomputers) as well as computers that are generally used in one place(such as conventional desktop computers, workstations, and/or servers).In certain embodiments, the electronic device 10 in the form of acomputer may be a model of a MACBOOK®, MACBOOK® PRO, MACBOOK AIR®,IMAC®, MAC® MINI, OR MAC PRO® available from Apple Inc. By way ofexample, the electronic device 10, taking the form of a notebookcomputer 10A, is illustrated in FIG. 2 in accordance with one embodimentof the present disclosure. The depicted computer 10A may include ahousing or enclosure 36, a display 18, input structures 22, and ports ofan I/O interface 24. In one embodiment, the input structures 22 (such asa keyboard and/or touchpad) may be used to interact with the computer10A, such as to start, control, or operate a GUI or applications runningon computer 10A. For example, a keyboard and/or touchpad may allow auser to navigate a user interface or application interface displayed ondisplay 18.

FIG. 3 depicts a front view of a handheld device 10B, which representsone embodiment of the electronic device 10. The handheld device 10B mayrepresent, for example, a portable phone, a media player, a personaldata organizer, a handheld game platform, or any combination of suchdevices. By way of example, the handheld device 10B may be a model of anIPOD® OR IPHONE® available from Apple Inc. of Cupertino, Calif. Thehandheld device 10B may include an enclosure 36 to protect interiorcomponents from physical damage and to shield them from electromagneticinterference. The enclosure 36 may surround the display 18. The I/Ointerfaces 24 may open through the enclosure 36 and may include, forexample, an I/O port for a hardwired connection for charging and/orcontent manipulation using a standard connector and protocol, such asthe Lightning connector provided by Apple Inc., a universal serial bus(USB), or other similar connector and protocol.

User input structures 22, in combination with the display 18, may allowa user to control the handheld device 10B. For example, the inputstructures 22 may activate or deactivate the handheld device 10B,navigate user interface to a home screen, a user-configurableapplication screen, and/or activate a voice-recognition feature of thehandheld device 10B. Other input structures 22 may provide volumecontrol, or may toggle between vibrate and ring modes. The inputstructures 22 may also include a microphone may obtain a user's voicefor various voice-related features, and a speaker may enable audioplayback and/or certain phone capabilities. The input structures 22 mayalso include a headphone input may provide a connection to externalspeakers and/or headphones.

FIG. 4 depicts a front view of another handheld device 10C, whichrepresents another embodiment of the electronic device 10. The handhelddevice 10C may represent, for example, a tablet computer, or one ofvarious portable computing devices. By way of example, the handhelddevice 10C may be a tablet-sized embodiment of the electronic device 10,which may be, for example, a model of an IPAD® available from Apple Inc.of Cupertino, Calif.

Turning to FIG. 5, a computer 10D may represent another embodiment ofthe electronic device 10 of FIG. 1. The computer 10D may be anycomputer, such as a desktop computer, a server, or a notebook computer,but may also be a standalone media player or video gaming machine. Byway of example, the computer 10D may be an IMAC®, a MACBOOK®, or othersimilar device by Apple Inc. It should be noted that the computer 10Dmay also represent a personal computer (PC) by another manufacturer. Asimilar enclosure 36 may be provided to protect and enclose internalcomponents of the computer 10D such as the display 18. In certainembodiments, a user of the computer 10D may interact with the computer10D using various input structures 22, such as the keyboard 22A or mouse22B, which may connect to the computer 10D.

Similarly, FIG. 6 depicts a wearable electronic device 10E representinganother embodiment of the electronic device 10 of FIG. 1 that may beconfigured to operate using the techniques described herein. By way ofexample, the wearable electronic device 10E, which may include awristband 38, may be an APPLE WATCH® by Apple Inc. However, in otherembodiments, the wearable electronic device 10E may include any wearableelectronic device such as, for example, a wearable exercise monitoringdevice (e.g., pedometer, accelerometer, heart rate monitor), or otherdevice by another manufacturer. The display 18 of the wearableelectronic device 10E may include a touch screen display 18 (e.g., LCD,OLED display, active-matrix organic light emitting diode (AMOLED)display, and so forth), as well as input structures 22, which may allowusers to interact with a user interface of the wearable electronicdevice 10E.

With the foregoing in mind, FIG. 7 illustrates an embodiment of theduplexer 26 that includes an EBD 41. As illustrated, the EBD 41 providesisolation between the receiver 27 and the transmitter 28 while enablingboth the receiver 27 and the transmitter 28 to utilize the antenna 20.As illustrated, the duplexer 26 may include a low-noise amplifier (LNA)42 that may be used to amplify received signals for the receiver 27. Insome embodiments, an iteration of the LNA 42 may be located within thereceiver 27 in addition to or alternative the LNA 42 within the duplexer26. In some embodiments, an iteration of the LNA 42 may be locatedwithin the receiver 27 in addition to or alternative the LNA 42 withinthe duplexer 26. The duplexer 26 may also include a power amplifier (PA)43 that receives signals from the transmitter 28. The PA 43 amplifiesthe signals to a suitable level to drive the transmission of the signalsvia the antenna 20. In some embodiments, an iteration of the PA 43 maybe located within the transmitter 28 in addition to or alternative thePA 43 within the duplexer 26. These signals are to be transmitted viathe antenna 20.

The EBD 41 includes a secondary winding 45 that may be used toselectively pass a signal from the antenna to the LNA 42 (and to thereceiver 27) via primary windings 46 and/or 47. Signals from the PA 43(and from the transmitter 28) are passed to antenna 20 via a line 48coupled between the primary windings 46 and 47. A balancing network 49of the EBD 41 may be used to actively replicate an impedance of theantenna 20 to maximize isolation between the receiver 27 and thetransmitter 28. However, if the impedance of the antenna 20 shifts, aduplexer function of the duplexer 26 is disturbed and the isolationbetween the receiver 27 and the transmitter 28 are degraded. Instead,the duplexer 26 may use an alternative arrangement of the EBD 41, suchas embodiments of the duplexer 26 illustrated in FIGS. 8-13, that reducethe insertion loss resulting from using the EBD 41 in FIG. 7 whileeliminating the antenna replica dependency of FIG. 7 to improveflexibility of frequencies used in the duplexer 26.

FIG. 8 is a simplified block diagram of an embodiment of the duplexer 26with an EBD 41 that does not include the antenna replica dependencypresent in FIG. 7. As illustrated, the duplexer 26 is coupled to theantenna 20 and provides selective access to and from the antenna 20 bythe receiver 27 and the transmitter 28 of the electronic device 10. Theduplexer 26 includes transmitter balun circuitry 58 having a transmitterbalun 59 and receiver balun circuitry 60 having a receiver balun 61. Thetransmitter 28 is coupled to a first side of the transmitter balun 59while the receiver 27 is coupled to a corresponding first side of thereceiver balun 61.

The transmitter balun circuitry 58 and the receiver balun circuitry 60each enables a corresponding path (e.g., between the antenna 20 and thereceiver 27/the transmitter 28) to be blocked or allowed. This selectiveblocking/passing may be set for the transmitter balun circuitry 58 usingan impedance gradient 62 coupled to a second side of the transmitterbalun 59 opposite the connection to the transmitter 28, and the statemay be set for the receiver balun circuitry 60 using an impedancegradient 64 coupled to a second side of the receiver balun 61 oppositethe connection to the receiver 27. The impedance gradients 62 and 64 maybe implemented using discrete lumped components or distributedcomponents that set desired impedances for certain frequencies and maycouple certain frequencies to ground 65 with a low impedance. Regardlessof implementation type, the impedance gradients 62 and 64 act as filtershaving a relative high impedance in a “pass” band compared to a relativelow impedance (e.g., short to ground 65) in a “block” band.

Furthermore, the transmitter balun 59 includes a winding 66 that mayproduce an electromagnetic field due to excitation due to the connectionof the winding 66 to the transmitter 28 and a common return 68 (e.g.,ground). The field generated at the winding 66 may cause resultingsignals in windings 70 and/or 72 depending on the frequency range of thesignals and the impedance provided by the impedance gradient 62 in thatfrequency range. The impedance gradient 62 is coupled to the winding 70and a connection of the winding 72 to a common return 74. A line 76 iscoupled between the windings 70 and 72 to enable the signals from thetransmitter 28 to the antenna 20 via an antenna balun 77 when thetransmitter balun 59 is set to pass transmission signals using theimpedance gradients 62 and/or 64.

The receiver balun 61 includes a winding 78 that may generate a signalbased on an electromagnetic field generated by windings 80 and/or 82based on the impedance gradient 64 providing an impedance to thereceiver balun 61 that enables passing of signals across the receiverbalun 61. A line 84 between the windings 80 and 82 couples the pair ofwindings 80 and 84 to the antenna balun 77. Specifically, the lines 76and 84 are coupled to opposite ends of a winding 86 of the antenna balun77. The impedance gradients 62 and 64 cause a transmission signal to bepassed to the line 76, when the duplexer 26 permits transmission ofsignals having a transmission frequency. The passing of the transmissionsignal causes the winding 86 to generate an electromagnetic field thatinduces a signal on a secondary winding 88 of the antenna balun 77 thatis passed to the antenna 20 to be broadcast.

The impedance gradients 62 and 64 cause a received signal to be passedfrom the antenna to the receiver 27, when the duplexer 26 permitssignals having a receive frequency using an impedance from the impedancegradient 64. Although the illustrated embodiment includes a singleantenna balun 77 to provide connection to the antenna 20, any othersuitable implementation used to transmit signals between the antenna 20and a corresponding lines 76 and 84.

FIG. 9 is a schematic diagram illustrating the duplexer 26 in atransmission mode for at least one transmission frequency. As previouslynoted, the impedance gradient 62 acts a filter that provides a highimpedance for a pass band. For example, the impedance gradient 62 mayselect an “open” position 100 instead of a “short” position 102. The“open” position 100 connects the winding 70 to a relatively highimpedance compared to a relatively low impedance provided when the shortposition 102 is selected to provide a low impedance path to ground 65.As illustrated, the impedance gradient 62 may be in a transmission modefor the transmission frequency. With the impedance gradient 62configured to provide a high impedance path for the winding 80 at thetransmission frequency, transmission signals from the transmitter 28 arepassed in a transmission path 104 across the transmitter balun 59 andultimately to the antenna 20.

The impedance gradient 64 functions similar to the impedance gradient 62except that the impedance gradient 64 is to block transmissionfrequencies from being transmitted to the receiver 27 when in thetransmission frequency. To achieve this isolation, the impedancegradient 64 is set to select between coupling the winding 80 to a “open”position 106 and a “short” position 108, each respectively similar tothe “open” position 100 and the “short” position 102. Since the duplexer26 is to block the transmission frequency from the receiver 27, theimpedance gradient 64 provides a low impedance connection to the winding80 for the transmission frequency. With the impedance gradient 62configured to provide a low impedance path for the winding 80 at thetransmission frequency, transmission signals from the antenna 20 arepassed in a transmission path 110 until being stopped from transferenceacross the receiver balun 61 due to the low impedance connectionprovided by the impedance gradient 64 to the winding 80.

Since the EBD 41 has two impedance gradients 62 and 64 that may becontrolled individually and block corresponding frequencies, the EBD 41may be used to implement the duplexer 26 as a frequency divisionduplexer. FIG. 10 is a schematic diagram illustrating the duplexer 26for at least one receive frequency. The receiver mode of the duplexer 26for the receive frequency includes the impedance gradient 62 couplingthe winding 70 to a low impedance path causing a transmission path 112to be blocked preventing transference of transmission signals across thetransmitter balun 59. Furthermore, the receiver mode of the duplexer 26for the receive frequency includes the impedance gradient 64 couplingthe winding 80 to a high impedance path causing received signals to bepassed along a receive path 114 from the antenna 20 to the receiver 27via receiver balun 61.

With the impedance gradient 62 configured to provide a high impedancepath for the winding 80 at the transmission frequency, transmissionsignals from the transmitter 28 are passed in a transmission path 104across windings 66 and 72 to the line 76 and ultimately to the antenna20.

Since the impedance gradients 62 and 64 may be implemented usingreal-word components, the high impedance and low impedance settings forimpedance gradients 62 and 64 may be values other than ideal short andopen values (e.g., 0Ω and ∞Ω). To address the non-ideal operation of theimpedance gradients 62 and 64, an additional component, an impedancetuner, may be used to compensate for such non-ideal values ofimpedances. Furthermore, a concern in operation of the EBD 41 can be anabrupt change in impedance at the transmission and receive frequencies.By using the impedance tuner, the demands on the impedance gradients 62and 64 may also be reduced. FIG. 11 illustrates an embodiment of theduplexer 26 with impedance tuners 120 and 122. Whereas the impedancegradients 62 and 64 act as filters, the impedance tuners 120 have a lowimpedance in the “pass” band for the respective balun and replicates theimpedance of the corresponding impedance gradient in the “block” band.In other words, in some embodiments, the impedance tuners 120 and 122may always provide a low impedance lower than the high impedance of acorresponding impedance gradient for passed frequencies while providinga similar low impedance that is provided by the corresponding impedancegradient for blocked frequencies.

The illustrated embodiment of the EBD 41 in FIG. 11 also includeswindings 124 and 126 that respectively supplement the windings 66 and78. However, in some embodiments, the windings 66 and 124 may becombined into a single winding, and the windings 78 and 126 may becombined into a single winding.

Since signals to the receiver 27 and from the transmitter 28 may bedifferential signals, some embodiments of the EBD 41 may addressdifferential transmittance of such signals. For instance, in FIG. 12,the EBD 41 includes a positive transmitter terminal 130 and a negativetransmitter terminal 132 that together form a differential signal fromthe transmitter 28 (e.g., via the PA 43). Thus, in the EBD 41 of FIG.12, the transmitter balun 59 may be used to convert the differentialsignal from the transmitter 28 to a single signal on the line 76.Similarly, the EBD 41 of FIG. 12 includes a positive receiver terminal134 and a negative receiver terminal 136 that together form adifferential signal to the receiver 27 (e.g., via the LNA 42). Thus, inthe EBD 41 of FIG. 12, the receiver balun 61 may be used to convert thesingle signal on the line 84 to a differential signal suitable for thereceiver 27.

The impedance gradients 62 and 64 and the impedance tuners 120 and 122have been illustrated on as coupled to the corresponding baluns at aside opposite side (e.g., secondary winding-side of the transmitterbalun 59) than the receiver 27 or the transmitter 28 in the foregoingembodiments. However, the impedance gradients 62 and 64 and theimpedance tuners 120 and 122 may be coupled to the same respective side(e.g., the primary winding-side of the transmitter balun 59) as thereceiver 27 or the transmitter 28. FIG. 13 illustrates a schematicdiagram of an embodiment of the duplexer 26 having such an arrangement.As illustrated, the transmitter 28 is coupled to the transmitter balun59 between the windings 66 and 124, and the receiver 27 is coupled tothe receiver balun 61 between the windings 78 and 126. Moreover, theimpedance gradient 62 is coupled between the winding 66 and ground 65instead of between the winding 70 and ground 65 illustrated in previousembodiments. Furthermore, the impedance tuner 120 is coupled between thewinding 124 and ground 65 instead of between the winding 72 and ground65 illustrated in previous embodiments. Moreover, the impedance gradient64 is coupled between the winding 78 and ground 65 instead of betweenthe winding 82 and ground 65 illustrated in previous embodiments.Furthermore, the impedance tuner 122 is coupled between the winding 126and ground 65 instead of between the winding 80 and ground 65illustrated in previous embodiments. In some embodiments, the impedancetuners 120 and 122 may be omitted from the duplexer 26 of FIG. 13.

FIG. 14 is flow diagram of a process 200 that may be used by theembodiments of the EBD 41 discussed in relation to FIGS. 8-13. Theprocess 200 includes the impedance gradient 62 providing a first lowimpedance to the transmitter balun 59 for a receive frequency band(block 202). The transmitter balun 59 uses the first low impedance toblock transmission signals in the receive frequency band from traversingthe transmitter balun 59 from the transmitter 28 to the antenna 20(block 204). The impedance gradient 64 provides a second low impedanceto the receiver balun 61 for a transmission frequency band (block 206).The first low impedance and the second low impedance may be the sameimpedance level or may be different impedance levels. The receiver balun61 then uses the second low impedance to block signals in thetransmission frequency band from traversing the receiver balun 61 to thereceiver 27 (block 208).

The impedance gradient 62 also provides a first high impedance to thetransmitter balun 59 for the transmission frequency band (block 210).The transmitter balun 59 uses the first high impedance to enable signalsin the transmission frequency band to traverse the transmitter balun 59from the transmitter 28 to the antenna 20 (block 212). The impedancegradient 64 provides a second high impedance to the receiver balun Noerrors found.61 for the receive frequency band (block 214). The receiverbalun 61 uses the second high impedance to enable signals in the receivefrequency band to traverse the receiver balun 61 from the antenna 20 tothe receiver 27 (block 216).

In addition, the impedance tuner 120 provides a third low impedance tothe transmitter balun 59 for the transmission frequency band to enhancetraversal of the transmitter balun 59 by the signals in the transmissionfrequency band. The third low impedance may be equal the first lowimpedance and/or the second low impedance. Alternatively, the third lowimpedance may be different than the first low impedance and the secondlow impedance. The impedance tuner 120 also provides the first lowimpedance to the transmitter balun 59 for the receive frequency band toaid the transmitter balun in blocking the signals in the receivefrequency band.

The impedance tuner 122 provides a fourth low impedance to the receiverbalun 61 for the receive frequency band to enhance traversal of thereceiver balun 61 by the signals in the receive frequency band. Thefourth low impedance may be equal the first low impedance, the secondlow impedance, and/or the third low impedance. Alternatively, the fourthlow impedance may be different than the first low impedance, the secondlow impedance, and the third low impedance. The impedance tuner 122 alsoprovides the second low impedance to the receiver balun 61 for thetransmission frequency band to aid the receiver balun 61 in blocking thesignals in the transmission frequency band.

The specific embodiments described above have been shown by way ofexample, and it should be understood that these embodiments may besusceptible to various modifications and alternative forms. For example,the methods may be applied for embodiments having different numbersand/or locations for antennas, different groupings, and/or differentnetworks. It should be further understood that the claims are notintended to be limited to the particular forms disclosed, but rather tocover all modifications, equivalents, and alternatives falling withinthe spirit and scope of this disclosure.

The techniques presented and claimed herein are referenced and appliedto material objects and concrete examples of a practical nature thatdemonstrably improve the present technical field and, as such, are notabstract, intangible or purely theoretical. Further, if any claimsappended to the end of this specification contain one or more elementsdesignated as “means for [perform]ing [a function] . . . ” or “step for[perform]ing [a function] . . . ”, it is intended that such elements areto be interpreted under 35 U.S.C. 112(f). However, for any claimscontaining elements designated in any other manner, it is intended thatsuch elements are not to be interpreted under 35 U.S.C. 112(f).

What is claimed is:
 1. An electrical balance duplexer for transmissionand reception of signals via an antenna, the electrical balance duplexercomprising: a transmitter balun having a first side coupled to atransmitter and a second side inductively coupled to the first side; anda transmitter impedance gradient coupled to the second side of thetransmitter balun between the transmitter balun and a ground connectionand configured to provide a first impedance to the ground connectionbased on a transmit frequency to cause one or more transmit signals totraverse the transmitter balun to the antenna, and provide a secondimpedance to the ground connection based on the transmit frequency, thesecond impedance being lower than the first impedance to block one ormore transmit signals from traversing the transmitter balun from theantenna by transmitting the one or more transmit signals to the groundconnection.
 2. The electrical balance duplexer of claim 1, wherein thefirst side of the transmitter balun comprises a plurality of windingswith the transmitter coupled between two of the plurality of windings.3. The electrical balance duplexer of claim 1, wherein the first side ofthe transmitter balun comprises a plurality of windings with thetransmitter coupled to an end of the plurality of windings.
 4. Theelectrical balance duplexer of claim 1, further comprising a transmitterimpedance tuner coupled to the second side of the transmitter balun, thetransmitter impedance tuner being configured to provide the firstimpedance and the second impedance to the transmitter balun.
 5. Theelectrical balance duplexer of claim 1, wherein the transmitter isfurther configured to provide the one or more transmit signals to thetransmitter balun as differential signals, and the transmitter beingconfigured to transmit the differential signals at the first side of thetransmitter balun at opposite ends of windings on the first side of thetransmitter balun.
 6. The electrical balance duplexer of claim 1,further comprising a receiver balun having a third side coupled to areceiver and a fourth side inductively coupled to the third side, and areceiver impedance gradient coupled to the fourth side of the receiverbalun between the receiver balun and the ground connection andconfigured to: provide a third impedance to the ground connection basedon a receive frequency to cause the one or more receive signals totraverse the receiver balun to the receiver from the antenna, andprovide a fourth impedance to the ground connection lower than the thirdimpedance based on the receive frequency to block the one or moretransmit signals from traversing the receiver balun to the receiver bytransmitting the one or more transmit signals to the ground connection.7. The electrical balance duplexer of claim 6, the third impedance beingequal to the first impedance, and the fourth impedance being equal tothe second impedance.
 8. The electrical balance duplexer of claim 6,wherein the third side of the receiver balun comprises a plurality ofwindings with the receiver coupled to two windings of the plurality ofwindings between the two windings.
 9. The electrical balance duplexer ofclaim 6, wherein the third side of the receiver balun comprises aplurality of windings with the transmitter coupled to one end of theplurality of windings.
 10. The electrical balance duplexer of claim 6,comprising a receiver impedance tuner coupled to the fourth side of thereceiver balun, the receiver impedance tuner being configured to providea low impedance in frequencies corresponding to the one or more receivesignals and to match an impedance of the receiver impedance gradient forthe one or more transmit signals.
 11. The electrical balance duplexer ofclaim 6, the receiver balun being configured to receive the one or morereceive signals as differential signals, and the receiver balun beingconfigured to provide the differential signals to the receiver from thethird side of the receiver balun at opposite ends of windings on thethird side of the receiver balun.
 12. The electrical balance duplexer ofclaim 6, comprising: a transmitter line coupled between windings of thesecond side of the transmitter balun that is configured to conduct theone or more transmit signals to the antenna from the transmitter balun;and a receiver line coupled between windings of the third side of thereceiver balun that is configured to conduct the one or more receivesignals to the receiver balun from the antenna.
 13. An electricalbalance duplexer for transmission and reception of signals via anantenna, the electrical balance duplexer comprising: a transmitter balunhaving a first side coupled to a transmitter and a second sideinductively coupled to the first side; a transmitter impedance gradientcoupled to the second side of the transmitter balun between thetransmitter balun and a ground connection and configured to: in areceive mode, provide a first impedance to the ground connection toblock one or more transmit signals from traversing the transmitter balunto the antenna based on a transmit frequency by transmitting the one ormore transmit signals to the ground connection, and in a transmit mode,provide a second impedance to the ground connection higher than thefirst impedance to pass the one or more transmit signals to the antennabased on the transmit frequency; a receiver balun having a first side ofthe receiver balun coupled to a receiver and a second side of thereceiver balun inductively coupled to the first side of the receiverbalun; and a receiver impedance gradient coupled to the second side ofthe receiver balun between the receiver balun and the ground connectionand configured to: in the transmit mode, provide a third impedance tothe ground connection to block the one or more transmit signals fromreaching the receiver based on a receive frequency by transmitting theone or more transmit signals to the ground connection, and in thereceive mode, provide a fourth impedance to the ground connection higherthan the third impedance to pass one or more receive signals from theantenna based on the transmit frequency.
 14. The electrical balanceduplexer of claim 13, comprising an antenna balun that has a fifth sideof the antenna balun selectively coupled to the transmitter and thereceiver and a sixth side of the antenna balun coupled to the antenna,the sixth side of the antenna balun being inductively coupled to thefifth side of the antenna balun.
 15. The electrical balance duplexer ofclaim 14, the transmitter and the receiver being selectively coupled atopposite ends of windings of the fifth side of the antenna balun. 16.The electrical balance duplexer of claim 14, the antenna and groundconnection being coupled to opposite ends of windings of the sixth sideof the antenna balun.
 17. The electrical balance duplexer of claim 13,the first impedance blocking the one or more transmit signals fromtraversing the transmitter balun by enabling the one or more transmitsignals to be transmitted to the ground connection, and the secondimpedance passing the one or more transmit signals by blocking the oneor more transmit signals from the ground connection.
 18. An electricalbalance duplexer for transmission and reception of signals via anantenna, the electrical balance duplexer comprising: a receiver balunhaving a first side coupled to a receiver and a second side inductivelycoupled to the first side; and a receiver impedance gradient coupled tothe second side of the receiver balun and between the receiver balun anda ground connection and configured to provide a first impedance to theground connection based on a receive frequency to cause one or morereceive signals to traverse the receiver balun to the receiver from theantenna, and provide a second impedance to the ground connection basedon the receive frequency, the second impedance being lower than thefirst impedance to block the one or more receive signals from traversingthe receiver balun to the receiver by transmitting the one or morereceive signals to the ground connection.
 19. The electrical balanceduplexer of claim 18, further comprising: a transmitter balun having athird side coupled to a transmitter and a fourth side inductivelycoupled to the third side; and a transmitter impedance gradient coupledto the fourth side of the transmitter balun between the transmitterbalun and the ground connection and configured to provide a thirdimpedance based on a transmit frequency to cause one or more transmitsignals to traverse the transmitter balun to the antenna, and provide afourth impedance based on the transmit frequency, the fourth impedancebeing lower than the third impedance to block the one or more transmitsignals from traversing the transmitter balun to the antenna bytransmitting the one or more transmit signals to the ground connection.20. The electrical balance duplexer of claim 19, comprising a receiveconduit coupled between the antenna and a first center tap of coils ofthe second side, and a transmit conduit between the antenna and a secondcenter tap of coils of the fourth side.